Corner horn



July 17, 1956 w. A. RICE 2,754,926

CORNER HORN 2 Sheets-Sheet l /7 4 lNvENToR j 0 20 3 7 ATTORNEYS July 17, 1956 w. A. RICE 2,754,926

CORNER HORN Maar/v @c5 BY m @ab @a ATTORNEYS CORNER HORN Warren A. Rice, Ypsilanti, Mich., assigner to Asa M. Stackhouse, Ann Arbor, Mich., trustee Application November 26, 1954, Serial No. 471,395

2 Claims. (Cl. 181-31) The present invention is directed to a corner horn or speaker enclosure for use in high fidelity audio units and more particularly to a low frequency speaker enclosure or horn adaptable to use in a typical room of a dwelling house as a piece of room furnishing and locatable in any convenient corner where two planar wall surfaces intersect.

Corner horns are generally old in the art and the contributions of Klipsch disclosed in United States Letters Patent 2,310,243 and 2,373,692 are well known to lovers of high fidelity sound reproduction. Until now the Klipsch devices represented a high point in low frequency horns. As in the contributions of Klipsch, the present invention is directed to a low frequency corner horn wherein the unique structural form thereof utilizes the intersecting walls of the room for vertical flare extension, and thereby obtains increased efliciency of sound reproduction in the lower frequency extreme of audible sound. In addition the structural innovations herein presented provide greater compactness of the unit and accommodations for high frequency speaker installation while using unobstructed vertical walls for sound reproduction.

It is one of the objects of this invention to teach a structure capable of achieving eiciencies of forty per cent or better in the low frequency range. Efficiency in any given frequency range is determinative of reproduction fidelity in that it represents the amount of oscillatory vibrations actually available which are transduced to sound, i` e., electrical to air transduction efficiency.

lt is another object of the present invention to present an unfolded type of corner horn wherein distortion in the movement of the sound column around corners is substantially eliminated.

Another object is to provide a simple structure easy to fabricate and economical to produce.

A still further object is to provide a corner horn which is acceptable in a room setting and which is adapted for mounting of high and low frequency speakers.

Other objects of the invention will become increasingly apparent as the description proceeds.

In the drawings:

Figure 1 is a perspective view of a corner horn built in accordance with the present invention and having a portion of the face panel cut away to indicate its overall structural simplicity.

Figure 2 is a front elevation view of a corner horn with the fore panel removed in accord with this invention and with the speaker position illustrated in phantom line.

Figure 3 is a top plan view of a corner horn in accord with this invention.

Figure 4 is a section on IV-IV of Figure 2.

Figure 5 is a section V-V of Figure 2.

` Figure 6 is a diagram showing the low frequency eiciencies of the horn of the present invention under average furnished room conditions as compared to the most efficient horn presently known and also shows the low frequency efficiencies of the horn of thepresent invention as compared to the most efficient horn presently known under sound room acoustical conditions.

niteci States Patent O The limit of audible sound in the lowest musical note (perhaps the organ) is about 16 cycles per second. Presently most speaker enclosures or horns are capable only of delivering 10 to 12 per cent efficiencies in the audible low frequency range. As a consequence, high delity or faithful sound reproduction has been hampered by an inability to efficiently reproduce sound because the transducing of an electrical impulse into an audible sound has been heretofore ineicient in the low frequency spectrum.

It has long been theoretically known that by carefully controlling the flare rate in the speaker enclosure or horn efficiencies could be enhanced in the low frequency range. it was necessary, however, to provide a long throat-tomouth gradual progression to do so. The volute type speakers were evolved and not infrequently the horns of greatest etiiciency, i. e., theatre sound systems, were monstrosities occupying a great amount of space. Because of the great dimensions involved such horns could not bring low frequency high fidelity into the home. Folded type horns utilizing wall and iioor planes for magnifying the length of flare were employed. Theoretical results brought about enhanced use of the walls for are extensions and efficiencies of the theatre horns were approximated in home size units. Most of these devices utilized a horizontal projection of the sound waves from side mouths confined by the floor and bounded by the walls so that a compact unit could deliver the approximate results of a long flare. Other horns employ tortuous sound column paths to compact and approximate the desirable long are. In sound room tests under ideal conditions the efficiencies of sound reproduction in such horns rated favorably with the larger theatre type horns of much larger dimensions. However, in actual home use difficulty was encountered by reason of obstructions such as furniture located proximate to the wall surfaces. These obstructional problems diminished the efficiencies in normal home use. By projecting the sound column upwardly as taught by the unique structure herein described, enhanced efficiencies are realized and obstruction distortion is substantially eliminated.

This result is accomplished uniquely in an unfolded type structure where the are rate in exponential values is unhampered by a plurality of direction changes where efficiencies are sacrificed and the mashing of tones often occurs. Mashing herein has reference to the total distortion occurring by reason of folding or corners constituting a tortuous path for the sound-air columns. Referring to Figure 1, the present invention consists of a basically unfolded horn in which the are is vertical and the mouths open so that the vertical walls of the room at the corner serve as a vertical extension of the tapered walls of the horn.

The liare rate between the throat area A and the broadening mouth B is calculated to increase in area by nine tenths (.9) times for each foot of vertical progression. For a 25 cycle knee in the efficiency or frequency respouse curves, this closest approaches the theoretical perfect flare rate and is not distorted by the circuitous paths adopted by prior horns.

The general structure of the present corner horn is symmetrical and oppositely identical with respect to the corner established by any two intersecting planar surfaces as for example walls X and Y. The flare rate is established by back plates 11 and 12 and hereinafter referred to as left back plate 11 and right back plate 12 as the corner horn is viewed frontally. Both the left and right back plates 11 and 12 are planar and rectilinear in form and the intersection of the two planar surfaces corresponds in flare to the slope of the back plates 11 and 12 as will be seen hereinafter.

Two inner end barriers 13 and 14, respectively left and .right are planar in form and are transversely positioned of this invention.

with respect to the back plates 11 and 12. These inner barriers 13 and 14 continue the desired volumetric llare rate established by the back plates 11 and 12, respectively, but as will be seen these inner barriers 13 and 14 confine the air column at the ends. The inner barriers 13 and 14 also establish a spaced relationship between the back plates 11 and 12 and planar inner baies 15 and 16 respectively. Exterior end barriers 17 and 18 left and right respectively, serve no functional purpose but are illustrated as a mere vertical housing of the inner functional barriers 13 and 14. The inner baies 15 and 16 establish -the inner limits of the ared area and intersect the inner end barriers 13 and 14 respectively and close upon each other at their planar intersection 19. Notches 20 are provided extending from the planar intersection of the generally rectilinear inner baffles and 16 at the bottom of the baies 15 and 16. The notches 20 thus define an opening to the flare portion 21 which is restricted in size to form the throat portion 22 of the horn. The size of this opening is determined from the characteristics of a given speaker as will be hereinafter more completely described.

Thus a flare is established by the positioning of the recited planar members which, depending on size, corresponds from bottom to top with the aforementioned desired area progression in low frequency horns. When the structure thus far described is viewed from top or bottom (Figure 3) the vertical projection of planar members defines a corner conforming structure with the top back portion coinciding in position with the intersecting Walls forming the wall corner, and at the bottom indented but paralleling the right angles of the wall corner.

A flatbase 23 is provided which is generally a right triangle in form with right angle truncations at two of the vertices corresponding in position to the intersection of the exterior end barriers 17 and 1S. This base 23 sits flatly on the oor set out from the corner defined by the intersection of walls X and Y, and closes at the bottom with the intersection of the back plates 11 and 12, inner baies 15 and 16, and end barriers 13 and 14. Thus all of the planar members defining the ared volume hare upward and outward from the base 23. The back plates 11'and 12 have a convenient vertical height and match the height of the inner batiies 15 and 16 and the end barriers 17 and 18 and internal barriers 13 and 14.

A horizontal upper shelf member 24 is provided which is triangular in form and which is attached to the outside faces of the inner baflies 15 and 16 and projects outwardly therefrom. In parallel spaced relation to the upper shelf 24 a lower shelf 25 is provided which is similar in shape, size and orientation to the upper shelf 24. The chamber 26 thus confined by the two shelves 24 and 25 provides a mounting area for high frequency or midrange speakers. Depending upon the size of any particular high frequency speaker the spaced relationship between shelves may be correspondingly great or small.

In the space 27 defined by the lower shelf 25 and the base 23 mounting means 28 are provided for the positioning of a low frequency audio or speaker unit 29 schematically indicated in Figures l and 2. The particular speaker 29 preferable in this horn structure is such as to be suitable for back loading and preferably of the well known coaxial or triaxial types, although any type of back loading low frequency speaker or woofer may be installed with appropriate size modifications not outside of the spirit A generally triangular planar guide plate 30, having its apex on the planar intersection 19 at the opening formed by the notches 20, is positioned behind the speaker 29 and extends upward to meet the lower shelf 25. It will be seen that the guide plate 30 coincides along its edges with the inner baffles 15 and 16. The connection of the guide plate 30 with the lower shelf 25 is a planar intersection about midway of the depth of the shelf member 25.

A generally rectangular front panel closure 31 is `fitted to segregate the high frequency chamber 26 and the space 27 confining the low frequency speaker. The closure 31 may be covered with a mesh material 32 and a frontal opening is provided at 33 in the backing material comprising the base material of the closure 31. The panel closure 31 is peripherally sealed around the low frequency speaker space 27. Acoustical deadening material effective only in the high frequency range for sound absorption is used to line the low frequency speaker space 27 1t will thus be noted that a pair of merged and flared air columns are provided opening outwardly from a common throat area 22 adjacent the base, and in communication with the low frequency speaker space 27. It will further be noted that upon positioning the corner horn described in the corner of a room the flare is extended by reason of the vertical openings at the back coinciding with the vertical room Walls X and Y.

As an example of a specic installation the following dimensional analysis is given wherein the horn is adapted to serve a l2 inch low frequency back loading speaker and a high frequency speaker or tweeter. The horn is 36 inches in vertical height and the mouth at the upper termination of the flared column is 23 linches long on either wall sideand 5 inches in Width. These dimensions establish the size of the base 23 since the exterior end barriers 17 and 1S drop vertically from the mouth of the dared column. The inner end barriers 13 and 14 are symmetrically opposite and are rectilinear in form and are tapered to complete the desired volumetric relationship to meet the base 23 approximately l2 inches back from the vertical seam established by the joining of inner bafiles 15 and 16. This positioning of the inner end barriers 13 and 14 with the base 23 establishes the horizontal size of notches 20. The vertical height of the notch opening 2t) with the particular speaker is established at 3 inches. The notches 20 as provided in both of the bafes 15 and 16 are l2 inches by 3.inches. The prism-like low frequency speaker compartment 27 has an 'approximate height of about 14 inches and is closed at the top by the shelf 25 andguide plate 313. The frontal closure 31 is provided with one opening 33 into the low frequency speaker compartment S inches in diameter. The l2 inch back loading speaker is attached by suitable means (bolted with gasket) to the rear of the closure as indicated in Figure l. Another suitable opening is provided (not shown) which opens through the front closure 31 to the high frequency speaker chamber 26. ln this specific example the flare rate of nine tenths (.9) for one foot of vertical progression is satisfied by a throat area of 75 square inches and a broadened mouth of 200 square inches.

The inner Walls of the low frequency compartment 27 are coated with high-frequency sound-absorbing material. The closure 31 is peripherally sealed to close olf the front of the low frequency space 27 from the high frequency speaker compartment 26.

It will be understood that identical horns, excepting size, may be provided to serve any given set of high and low frequency speakers.

From the chart in Figure 6 it will be seen that the performance characteristics show an eiciency of this horn in the low frequency range unmatched in any horn having dimensions suitable for ordinary living quarters, and the efficiency is indicated as considerably in excess of any presently known horns.

Tests were conducted kwith respect to eticiency under both sound room conditions, and in an average furnished room having an eight foot ceiling height. Figure 6 shows the results of these tests in graphic form. An amazing correlation of these results is noted and it is believed that distortion is eliminated by the vertical use of room Walls as flare extensions thereby avoiding room furnishings as obstacles. Further, the obvious'simplicity of the unfolded type horn eliminates correction factors required in folded horns Where the sound column is compacted to go around sharp corners and bends. In the graph, which constitutes Figure 6, the heavy solid line represents the operation of a corner horn in accord with the present invention under sound room conditions with the frequency in cycles per second plotted against relative sound intensity in decibels. The heavy dashed line represents the corner horn of this invention under normal furnished room conditions. The lighter solid line represents one of the best corner horns previously known operated under sound room conditions. The lighter dashed line indicates the operation of the best previously known horn under normal furnished room conditions.

Computed percentage efliciency is superimposed on the decibel scale and can be read directly on the diagram of Figure 6.

Having thus described a specic embodiment of a structure in accord with the present invention it will he understood that modications falling within the spirit of the hereinafter appended claims are intended to be included in the scope of the present invention unless the claims negative such inclusion.

I claim:

l. In a horn adapted for low frequency audio ranges the combination including: two pairs of spaced and nonparallel planar members defining two merged and identically upwardly flared sound passages; a base; two inwardly slanting side members dening the lateral extension of said passages; the innermost of said planar members being open proximate to said base and defining a throat therethrough; a horizontal member parallel to said base and intersecting said innermost planar member and defining with said base and said innermost planar member a speaker mounting chamber communicating through said throat with said upwardly ared passages; and a front panel with sealing means for the attachment of a low frequency speaker and having a frontal opening therethrough on the speaker axis.

2. in a low frequency horn the combination including: two outer panels generally paralleling vertically rising walls in the corner of a room; two inner panels variably spaced apart from said outer panels; end pieces upwardly slanting to close the ends of said panels and detining with said panels two merged upwardly flared and slanting and substantially identical passageways; a base; rectilinear notches in the inner of said panels dening a throat therethrough; a horizontal member parallel to said base and spaced apart therefrom and defining with said base and said innermost panels a speaker mounting chamber communicating through said throat with said upwardly flared passages; and a front panel closing said speaker chamber and adapted for sealing a speaker thereto and having an opening therethrough on the axis of a speaker diaphragm.

References Cited in the le of this patent UNITED STATES PATENTS Klipsch Feb. 9, 1943 Klipsch Apr. 17, 1945 OTHER REFERENCES 

